Merge pull request #1343 from drewejohnson/default-dict-weighted-yields

Use defaultdict when weighting fission yields

openmc/deplete/abc.py

@@ -5,6 +5,7 @@ to run a full depletion simulation.
 """
 
 from collections import namedtuple
+from collections import defaultdict
 from collections.abc import Iterable
 import os
 from pathlib import Path
@@ -376,14 +377,17 @@ class FissionYieldHelper(ABC):
 
     Attributes
     ----------
-    constant_yields : dict of str to :class:`openmc.deplete.FissionYield`
+    constant_yields : collections.defaultdict
         Fission yields for all nuclides that only have one set of
-        fission yield data. Can be accessed as ``{parent: {product: yield}}``
+        fission yield data. Dictionary of form ``{str: {str: float}}``
+        representing yields for ``{parent: {product: yield}}``. Default
+        return object is an empty dictionary
+
     """
 
     def __init__(self, chain_nuclides):
         self._chain_nuclides = {}
-        self._constant_yields = {}
+        self._constant_yields = defaultdict(dict)
 
         # Get all nuclides with fission yield data
         for nuc in chain_nuclides:
@@ -407,14 +411,16 @@ class FissionYieldHelper(ABC):
         Parameters
         ----------
         local_mat_index : int
-            Index for material tracked on this process that
-            exists in :attr:`local_mat_index` and fits within
-            the first axis in :attr:`results`
+            Index for the material with requested fission yields.
+            Should correspond to the material represented in
+            ``mat_indexes[local_mat_index]`` during
+            :meth:`generate_tallies`.
 
         Returns
         -------
-        library : dict
-            Dictionary of ``{parent: {product: fyield}}``
+        library : collections.abc.Mapping
+            Dictionary-like object mapping ``{str: {str: float}``.
+            This reflects fission yields for ``{parent: {product: fyield}}``.
         """
 
     @staticmethod

openmc/deplete/chain.py

@@ -398,7 +398,7 @@ class Chain(object):
             clean_indentation(root_elem)
             tree.write(str(filename), encoding='utf-8')
 
-    def get_thermal_fission_yields(self):
+    def get_default_fission_yields(self):
         """Return fission yields at lowest incident neutron energy
 
         Used as the default set of fission yields for :meth:`form_matrix`
@@ -412,7 +412,7 @@ class Chain(object):
             names of nuclides with yield data and ``f_yield``
             is a float for the fission yield.
         """
-        out = {}
+        out = defaultdict(dict)
         for nuc in self.nuclides:
             if nuc.yield_data is None:
                 continue
@@ -440,13 +440,13 @@ class Chain(object):
 
         See Also
         --------
-        :meth:`get_thermal_fission_yields`
+        :meth:`get_default_fission_yields`
         """
         matrix = defaultdict(float)
         reactions = set()
 
         if fission_yields is None:
-            fission_yields = self.get_thermal_fission_yields()
+            fission_yields = self.get_default_fission_yields()
 
         for i, nuc in enumerate(self.nuclides):
 
@@ -721,7 +721,7 @@ class Chain(object):
     @property
     def fission_yields(self):
         if self._fission_yields is None:
-            self._fission_yields = [self.get_thermal_fission_yields()]
+            self._fission_yields = [self.get_default_fission_yields()]
         return self._fission_yields
 
     @fission_yields.setter

openmc/deplete/helpers.py

@@ -5,6 +5,7 @@ from copy import deepcopy
 from itertools import product
 from numbers import Real
 import bisect
+from collections import defaultdict
 
 from numpy import dot, zeros, newaxis
 
@@ -179,9 +180,11 @@ class ConstantFissionYieldHelper(FissionYieldHelper):
 
     Attributes
     ----------
-    constant_yields : dict of str to :class:`openmc.deplete.FissionYield`
+    constant_yields : collections.defaultdict
         Fission yields for all nuclides that only have one set of
-        fission yield data. Can be accessed as ``{parent: {product: yield}}``
+        fission yield data. Dictionary of form ``{str: {str: float}}``
+        representing yields for ``{parent: {product: yield}}``. Default
+        return object is an empty dictionary
     energy : float
         Energy of fission yield libraries.
     """
@@ -237,7 +240,7 @@ class ConstantFissionYieldHelper(FissionYieldHelper):
 
         Returns
         -------
-        library : dict
+        library : collections.defaultdict
             Dictionary of ``{parent: {product: fyield}}``
         """
         return self.constant_yields
@@ -282,6 +285,11 @@ class FissionYieldCutoffHelper(TalliedFissionYieldHelper):
     fast_yields : dict
         Dictionary of the form ``{parent: {product: yield}}``
         with fast yields
+    constant_yields : collections.defaultdict
+        Fission yields for all nuclides that only have one set of
+        fission yield data. Dictionary of form ``{str: {str: float}}``
+        representing yields for ``{parent: {product: yield}}``. Default
+        return object is an empty dictionary
     results : numpy.ndarray
         Array of fission rate fractions with shape
         ``(n_mats, 2, n_nucs)``. ``results[:, 0]``
@@ -417,7 +425,7 @@ class FissionYieldCutoffHelper(TalliedFissionYieldHelper):
 
         Returns
         -------
-        library : dict
+        library : collections.defaultdict
             Dictionary of ``{parent: {product: fyield}}``
         """
         yields = self.constant_yields
@@ -469,9 +477,11 @@ class AveragedFissionYieldHelper(TalliedFissionYieldHelper):
 
     Attributes
     ----------
-    constant_yields : dict of str to :class:`openmc.deplete.FissionYield`
+    constant_yields : collections.defaultdict
         Fission yields for all nuclides that only have one set of
-        fission yield data. Can be accessed as ``{parent: {product: yield}}``
+        fission yield data. Dictionary of form ``{str: {str: float}}``
+        representing yields for ``{parent: {product: yield}}``. Default
+        return object is an empty dictionary
     results : None or numpy.ndarray
         If tallies have been generated and unpacked, then the array will
         have shape ``(n_mats, n_tnucs)``, where ``n_mats`` is the number
@@ -569,12 +579,13 @@ class AveragedFissionYieldHelper(TalliedFissionYieldHelper):
 
         Returns
         -------
-        library : dict
-            Dictionary of ``{parent: {product: fyield}}``
+        library : collections.defaultdict
+            Dictionary of ``{parent: {product: fyield}}``. Default return
+            value is an empty dictionary
         """
         if not self._tally_nucs:
             return self.constant_yields
-        mat_yields = {}
+        mat_yields = defaultdict(dict)
         average_energies = self.results[local_mat_index]
         for avg_e, nuc in zip(average_energies, self._tally_nucs):
             nuc_energies = nuc.yield_energies

tests/dummy_operator.py

@@ -83,7 +83,7 @@ class TestChain(object):
     fission_yields = [None]
 
     @staticmethod
-    def get_thermal_fission_yields():
+    def get_default_fission_yields():
         return None
 
     def form_matrix(self, rates, _fission_yields=None):

tests/unit_tests/test_deplete_chain.py

@@ -385,13 +385,13 @@ def test_set_alpha_branches():
 def test_simple_fission_yields(simple_chain):
     """Check the default fission yields that can be used to form the matrix
     """
-    fission_yields = simple_chain.get_thermal_fission_yields()
+    fission_yields = simple_chain.get_default_fission_yields()
     assert fission_yields == {"C": {"A": 0.0292737, "B": 0.002566345}}
 
 
 def test_fission_yield_attribute(simple_chain):
     """Test the fission_yields property"""
-    thermal_yields = simple_chain.get_thermal_fission_yields()
+    thermal_yields = simple_chain.get_default_fission_yields()
     # generate default with property
     assert simple_chain.fission_yields[0] == thermal_yields
     empty_chain = Chain()